Method of making self-promoted hydrotreating catalysts

ABSTRACT

Self-promoted molybdenum and tungsten sulfide hydrotreating catalysts are prepared by heating one or more water soluble catalyst precursors in a non-oxidizing atmosphere in the presence of sulfur at a temperature of at least about 200° C. The precursors will be one or more compounds of the formula ML(Mo y  W 1-y  O 4 ) wherein M is one or more promoter metals selected from the group consisting essentially of Mn, Fe, Co, Ni, Cu, Zn and mixtures thereof, wherein O≦y≦1 and wherein L is a nitrogen containing, neutral multidentate, chelating ligand. In a preferred embodiment the ligand L will comprise one or more chelating alkyl di or triamines and the non-oxidizing atmosphere will comprise H 2  S.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Ser. No. 603,834filed on Apr. 25, 1984 now abandoned which is a Rule 60 Continuation ofU.S. Ser. No. 454,220 (abandoned) which was filed on Dec. 29, 1982.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to self-promoted molybdenum and tungsten sulfidehydrotreating catalysts. More particularly, this invention relates toself-promoted molybdenum and tungsten sulfide hydrotreating catalystsproduced by heating one or more water soluble molybdate and/or tungstatecatalyst precursors containing the promoter metal as part of theprecursor molecule in the presence of sulfur at elevated temperature fora time sufficient to form said self-promoted catalyst.

2. Background of the Disclosure

The petroleum industry is increasingly turning to coal, tar sands, heavycrudes and resids as sources for future feedstocks. Feedstocks derivedfrom these heavy materials contain more sulfur and nitrogen thanfeedstocks derived from more conventional crude oils. Such feedstocksare commonly referred to as being dirty feeds. These feeds thereforerequire a considerable amount of upgrading in order to obtain usableproducts therefrom, such upgrading or refining generally beingaccomplished by hydrotreating process which are well-known in theindustry.

These processes require the treating with hydrogen of varioushydrocarbon fractions, or whole heavy feeds, or feedstocks, in thepresence of hydrotreating catalysts to effect conversion of at least aportion of the feeds, or feedstocks or lower molecular weighthydrocarbons, or to effect the removal of unwanted components, orcompounds, or their conversion to innocuous or less undesirablecompounds. Hydrotreating may be applied to a variety of feedstocks,e.g., solvents, light, middle, or heavy distillate feeds and residualfeeds, or fuels. In hydrotreating relatively light feeds, the feeds aretreated with hydrogen, often to improve such compounds in the presenceof hydrogen, which processes are collectively known as hydrotreating orhydrorefining processes, it being understood that hydrorefining alsoincludes some hydrogenation of aromatic and unsaturated aliphatichydrocarbons. Thus, U.S. Pat. No. 2,914,462 discloses the use ofmolybdenum sulfide for hydrodesulfurizing gas oil and U.S. Pat. No.3,148,135 discloses the use of molybdenum sulfide for hydrorefiningsulfur and nitrogen-containing hydrocarbon oils. U.S. Pat. No.2,715,603, discloses the use of molybdenum sulfide as a catalyst for thehydrogenation of heavy oils, while U.S. Pat. No. 3,074,783 discloses theuse of molybdenum sulfides for producing sulfur-free hydrogen and carbondioxide, wherein the molybdenum sulfide converts carbonyl sulfide tohydrogen sulfide. Molybdenum and tungsten sulfides have other uses ascatalysts, including hydrogenation, methanation, water gas shift, etc.reactions.

In general, with molybdenum and other transition metal sulfide catalystsas well as with other types of catalysts, higher catalyst surface areasgenerally result in more active catalysts than similar catalysts withlower surface areas. Thus, those skilled in the art are constantlytrying to achieve catalysts that have higher surface areas. Morerecently, it has been disclosed in U.S. Pat. Nos. 4,243,553, and4,243,554 that molybdenum sulfide catalysts of relatively high surfacearea may be obtained by thermally decomposing selected thiomolybdatesalts at temperatures ranging from 300°-800° C. in the presence ofessentially inert, oxygen-free atmospheres. Suitable atmospheres aredisclosed as consisting of argon, a vacuum, nitrogen and hydrogen. InU.S. Pat. No. 4,243,554 an ammonium thiomolybdate salt is decomposed ata rate in excess of 15° C. per minute, whereas in U.S. Pat. No.4,243,553, a substituted ammonium thiomolybdate salt is thermallydecomposed at a very slow heating rate of from about 0.5° to 2° C./min.The processes disclosed in these patents are claimed to producemolybdenum disulfide catalysts having superior properties for water gasshift and methanation reactions and for catalyzed hydrogenation orhydrotreating reactions.

SUMMARY OF THE INVENTION

Self-promoted molybdenum and tungsten sulfide hydroprocessing catalystsare obtained by heating one or more water soluble catalyst precursors ofthe formula ML(Mo_(y) W_(1-y) O₄) in a non-oxidizing atmosphere in thepresence of sulfur at a temperature of at least about 200° C. for a timesufficient to form said catalyst, wherein M comprises one or moredivalent promoter metals selected from the group consisting essentiallyof Mn, Fe, Co, Ni, Cu, Zn and mixtures thereof, wherein y is any valueranging from 0 to 1, and wherein L is one or more, neutral,nitrogen-containing ligand at least one of which is a chelatingpolydentate ligand. In a preferred embodiment M will be selected fromthe group consisting of (a) Fe, Co, Ni and mixtures thereof and (b)mixtures of (a) with Mn, Cu, Zn and mixtures thereof. In a particularlypreferred embodiment ligand L will have a denticity of six and will beeither three bidentate or two tridentate chelating, alkyl amine ligands,M will be selected from the group consisting essentially of Ni, Fe, Coand mixtures thereof and the non-oxidizing atmosphere will containhydrogen sulfide as the source of sulfur.

Hydroprocessing is meant to include any process that is carried out inthe presence of hydrogen, including, but not limited to, hydrocracking,hydrodenitrogenation, hydrodesulfurization, hydrogenation of aromaticand aliphatic unsaturated hydrocarbons, methanation, water gas shift,etc. These reactions include hydrotreating and hydrorefining reactions,the difference generally being thought of as more of a difference indegree than in kind, with hydrotreating conditions being more severethan hydrorefining conditions. Some of the catalysts of this inventionhave hydrotreating or hydrorefining activities substantially greaterthan that of conventional hydrotreating catalysts such as cobaltmolybdate on alumina.

The catalysts of this invention may be used in bulk form or supported ona suitable inorganic refractory oxide support such as alumina. Aparticularly significant advantage of this invention is that the watersolubility of the catalyst precursor permits the precursor to beimpregnated onto a suitable support such as alumina, via conventionalimpregnation techniques such as incipient wetness and adsorption.

DETAILED DESCRIPTION OF THE INVENTION

As hereinbefore stated, the catalyst precursor is a water solublemetallate having the formula ML(Mo_(y) W_(1-y) O₄) wherein M is one ormore divalent promoter metals selected from the group consisting of Mn,Fe, Co, Ni, Cu, Zn and mixtures thereof. Preferably M will be selectedfrom the group consisting of (a) Ni, Co, Fe and mixtures thereof and (b)mixtures of (a) with Zn, Cu, Mn and mixtures thereof. Still morepreferably M will be selected from the group consisting of Fe, Ni, Coand mixtures thereof. Thus, the promoter metal may be a single metalsuch as Ni in which case the precursor will have the formula(NiL)(Mo_(y) W_(1-y) O₄). Alternatively the promoter metal may be amixture of two, three, four, five or even six promoter metals. For thecase of two promoter metals, such as Ni and Co, the precursor will havethe formula [(Ni_(a) Co_(1-a))L](Mo_(y) W_(1-y) O₄) wherein 0<a<1. Inthe case of three promoter metals such as Ni, Co and Zn, the precursorwill have the formula of the form [(Ni_(a) Co_(b) Zn_(c))L](Mo_(y)W_(1-y) O₄) wherein 0<a, b or c<1 and a+b+c=1. Where there are fourmetals such as Fe, Ni, Co and Zn, the precursor will have the formula[(Fe_(a) Ni_(b) Co_(c) Zn_(d))L](Mo_(y) W_(1-y) O₄) wherein 0<a, b, c,or d<1 and a+b+c+d=1, and so on. The precursor may be a self promotedmolydate, tungstate or combination thereof. It it is only a molybdate itis obvious that y will have a value of 1. Alternatively, if theprecursor is a tungstate y will be zero.

The ligand L, will generally have a denticity of six and will be one ormore neutral, nitrogen containing ligands wherein at least one of saidligands is a multidentate chelating ligand which chelates the promotermetal cation to form a chelated promoter metal cation [ML]²⁺. Thus, thecatalytic metal oxide anion (Mo_(y) W_(1-y) O₄)²⁻ will be ionicallybound to the chelated promoter metal cation [ML]²⁺. By neutral is meantthat the ligand itself does not have a charge.

Those skilled in the art know that the term "ligand" is used todesignate functional coordinating groups which have one or more pairs ofelectrons available for the formation of coordinate bonds. Ligands thatcan form more than one bond with a metal ion are called polydentatewhile ligands that can form only one bond with a metal ion are calledmonodentate. Monodentate ligands are not capable of forming chelates.Hence, if one uses one or more species of monodentate ligands in theprecursor molecule, then one must also use at least one polydentatechelating ligand. Preferably L will be one or more polydentate chelatingLigands. The denticity of the ligand L will generally be six, becausethe promoter metal cations prefer six-fold coordination. Hence, if morethan one species of ligand is employed in the precursor molecule, thedenticity of the ligand species will usually add up to six. It should beunderstood that it is possible for ligand L to have a total denticity ofless than six, but in most cases L will have a total denticity of six.Thus, L will be three bidentate ligands, two tridentate ligands, amixture of a bidentate and a quadridentate ligand, a hexadentate ligandor a mixture of a polydentate ligand with monodentate ligands as long asthe combination has a total denticity of six. As has heretofor beenstated, it is preferred to use chelating bidentate and tridentateligands. In general, the ligands useful in this invention include alkyland aryl amines and nitrogen heterocycles. Illustrative but non-limitingexamples of ligands useful in the catalyst precursors of this inventionare set forth below.

Monodentate ligands will include NH₃ as well as alkyl and aryl aminessuch as ethyl amine, dimethyl amine, pyridine, etc. Useful chelatingbidentate amine ligands are illustrated by ethylenediamine,2,2'-bipyridine, 1,10-phenylene bis(dimethyl-amine), o-phenylenediamine, tetramethylethylenediamine and propane-1,3 diamine. Similarly,useful chelating tridentate amine ligands are represented by terpyridineand diethylenetriamine while triethylenetetramine is illustrative of auseful chelating quadradentate amine ligand. Useful chelatingpentadentate ligands include tetraethylenepentamine while sepulchrate(an octazacryptate) is illustrative of a suitable chelating hexadentateligand. However, as a practical matter it will be preferred to usechelating, polydentate alkyl amines for L. Illustrative, but notlimiting examples of alkyl amines that are useful in the catalystprecursor of this invention include ethylenediamine, diethylenetriamine,and tetraethylenetetramine. It is particularly preferred to usebidentate and tridentate alkyl amines such as ethylenediamine anddiethylenetriamine.

In general, the precursor salts useful for forming the catalysts of thisinvention may be prepared by mixing an aqueous solution of ammoniummolybdate and/or tungstate with an aqueous solution of the chelatedpromoter metal cation [ML]²⁺ which, in the presence of excess metallate,ligand and/or chelated promoter metal cation, will result in theformation of the precursor salt as a precipitate which is readilyrecovered. The chelating promoter cation is easily formed by, forexample, mixing an aqueous solution of one or more water solublepromoter metal salts with the ligand. The water soluble salt may be anywater soluble salt that is convenient to use such as a halide sulfate,perchlorate, acetate, nitrate, etc. Alternatively, an aqueous solutionof ammonium molybdate and/or tungstate may be mixed with the ligand withthe resulting solution mixed with an aqueous solution of promoter metalsalt or the salt can be added to the ligand and dissolved into thesolution of molybdate and/or tungstate. The catalyst precursorpreparation will be further understood by reference to the Examples,infra.

The catalysts of this invention may be used in bulk or supported on asuitable support, preferably supported on a suitable inorganicrefractory oxide support such as alumina. As previously stated, anadvantage of the catalyst precursors useful in this invention resides intheir water solubility which permits them to be supported on suitablesupport materials by techniques well-known in the art, such asimpregnation, incipient wetness and the like, the choice being left tothe convenience of the practitioner. When using the impregnationtechnique, the aqueous impregnating solution will be contacted with thesupport for a time sufficient to deposit the precursor material onto thesupport either by selective adsorption or alternatively, the excesswater may be evaporated during drying, leaving behind the precursorsalt. Advantageously, the incipient wetness techniques may be usedwhereby just enough of an aqueous precursor salt solution is added todampen and fill the pores of the support.

The catalysts of this invention may be prepared by heating one or morecatalyst precursor salts, bulk or supported, in the presence of sulfurin a non-oxidizing atmosphere, at a temperature of at least about 200°C. for a time sufficient to form the catalyst. Preferably the sulfurrequired during the formation of the catalyst will be present in theform of a sulfur bearing compound and in an amount in excess of thatrequired to form the catalyst. Thus, it is preferred that the catalystbe formed by heating the precursor in the presence of sulfur or,preferably in the presence of a sulfur bearing compound which can be oneor more solids, liquids, gases or mixtures thereof. Mixtures of hydrogenand H₂ S have been found to be particularly preferred. Preferably thetemperature will range between from about 250°-600° C., more preferablyfrom about 250°-500° C. and still more preferably from about 300°-400°C. The non-oxidizing atmosphere may be inert or net reducing.

As discussed under Background of the Disclosure, molybdenum and tungstensulfide catalysts have many uses, including hydrotreating. Hydrotreatingconditions vary considerably depending on the nature of the hydrocarbonbeing hydrotreated, the nature of the impurities or contaminants to bereacted or removed, and, inter alia, the extent of conversion desired,if any. In general however, the following are typical conditions forhydrotreating a naphtha boiling within a range of from about 25° C. toabout 210° C., a diesel fuel boiling within a range of from about 170°C. to 350° C., a heavy gas oil boiling within a range of from about 325°C. to about 475° C., a lube oil feed boiling within a range of fromabout 290°-500° C., or residuum containing from about 10 percent toabout 50 percent of material boiling above about 575° C.

    __________________________________________________________________________                             Space Hydrogen                                                          Pressure                                                                            Velocity                                                                            Gas Rate                                       Feed        Temp., °C.                                                                    psig  V/V/Hr                                                                              SCF/B                                          __________________________________________________________________________    Naphtha                                                                              Typical                                                                            100-370                                                                              150-800                                                                              0.5-10                                                                             100-2000                                       Diesel Typical                                                                            200-400                                                                              250-1500                                                                            0.5-6 500-6000                                       Heavy  Typical                                                                            260-430                                                                              250-2500                                                                            0.3-4 1000-6000                                      Lube Oil                                                                             Typical                                                                            200-450                                                                              100-3000                                                                            0.2-5   100-10,000                                   Residuum                                                                             Typical                                                                            340-450                                                                              1000-5000                                                                           0.1-2  2000-10,000                                   __________________________________________________________________________

The invention will be further understood by reference to the followingexamples.

EXAMPLES Catalyst Precursor Preparation

A tris(ethylenediamine) nickel molybdate Ni(en)₃ MoO₄ catalyst precursorwas prepared by dissolving ammonium molybdate into ethylenediamine (en)and the resulting solution cooled to 0° C. in an ice bath. An aqueoussolution of nickel chloride was slowly added, in aliquots, to the abovesolution, with agitation after the addition of each aliquot. Aprecipitate was formed and recovered by vacuum filtration. Thisprecipitate was Ni(en)₃ MoO₄ and was washed with distilled water andacetone and then dried in a vacuum oven at 50° C. for three hours. Theresulting cake was screened, pelletized, sized to 20/40 mesh (Tyler).More specifically, 20.5 gm of (NH₄)₆ Mo₇ O₂₄.4H₂ O (ammoniumheptamolybdate) was added to 500 ml of ethylene-diamine (en) in a 250 mlErlenmeyer flask. This amount of en was in excess of thatstoichiometrically required to form the precursor and the excess aidedin precipitating same from solution. From 40 to 50 cc of distilled H₂ Owas used twice to wash off any solid or solution remaining on the sidesof the flask. The resulting solution was cooled to 0° C. in an ice bathand kept in the bath for the duration of the preparation. In a separateflask 27 gm of NiCl₂.6H₂ O were dissolved into 300 ml of distilled H₂ O.This Ni²⁺ solution was added slowly, in aliquots, to the (NH₄)₂ MoO₄ /enaqueous solution with agitation after each addition. A precipitateformed immediately. This precipitate was separated out by vacuumfiltration through a Buchner funnel. The product, Ni(en)₃ MoO₄, waswashed with distilled H₂ O, then with ethanol, and dried under vacuumfor 16-24 hrs. 46.0 gm of Ni(en)₃ MoO₄ were recovered.

This same procedure was used for the preparation of Co(en)₃ MoO₄, exceptthat an appropriate amount of CoCl₂.6H₂ O was used instead of NiCl₂.6H₂O.

To form a supported catalyst, 43 grams of Co(en)₃ MoO₄ were dissolvedinto 140 cc of distilled water. Sixty grams of a reforming grade ofγ-Al₂ O₃ (Englehard Industries), which had been calcined overnight at500° C., were impregnated with this solution via the incipient wetnesstechnique using four successive aliquots. After each aliquot was addedto the alumina support, the impregnate was dried under vacuum at about100° C. for six hours. The final impregnate was ground and pelletizedusing a 4% aqueous solution of polyvinyl alcohol as a binder. The bulkNi(en)₃ MoO₄ was also pelletized using the same technique. Finally,another sample of Co(en)₃ MoO₄ was prepared and pelletized as above inbulk.

The pelletized catalyst precursors were placed into a stainless steelreactor at 100° C. at atmospheric pressure where they were purged forone hour under nitrogen. Ten percent of hydrogen sulfide in hydrogen wasintroduced into the reactor at a space velocity of 0.75 SCF/hr for each10 cc of catalyst in the reactor. The temperature in the reactor wasthen raised to 325°-360° C. and kept at this temperature for one tothree hours to form the catalyst after which the temperature in thereactor was lowered to 100° C., the H₂ S/H₂ gas flow was stopped and thereactor was purged with nitrogen until room temperature was reached.

Reaction Conditions

At least about 20 cc of each catalyst was loaded into a stainless steel,fixed-bed reactor. The conditions in the reactor were as set forthbelow:

    ______________________________________                                        Temperature        325° C.                                             Pressure           3.15 MPa                                                   Hydrogen rate      3000 SCF/bbl                                               LHSV               2, 3 and 4 V/V/Hr.                                         ______________________________________                                    

The liquid product was analyzed for sulfur by X-ray fluorescence and fornitrogen by combustion analysis. The feedstock used was a lightcatalytic cycle oil (LCCO) that was about 20 wt.% paraffinic havingproperties sets forth in Table 1.

In all of these experiments, the results obtained from the catalysts ofthis invention were compared to results obtained for commercial HDS andHDN catalysts comprising cobalt molybdate on γ-Al₂ O₃ and nickelmolybdate on γ-Al₂ O₃, respectively. The cobalt molybdate comprised 12.5percent molybdenum oxide and 3.5 percent cobalt oxide supported on thegamma alumina and the nickel molybdate comprised 18 percent molybdenumoxide and 3.5 percent nickel oxide on gamma alumina. These commercialcatalysts were sulfided employing the same procedure used to form thecatalysts of this invention, except that the temperature was 360° C. forone hour.

EXAMPLE 1

In this experiment, the LCCO feed was hydrotreated at an LHSV of 2comparing two of the catalysts of this invention to the commercialcobalt molydate on alumina HDS catalyst. The results are set forth inTable 2.

EXAMPLE 2

This experiment was the same as in Example 1 except that the LHSV was 3.The results are shown in Table 3.

EXAMPLE 3

In this experiment, the unsupported catalyst of this invention preparedfrom the Co(en)₃ MoO₄ was compared to the commercial HDN catalyst, theresults of which are shown in Table 4. These results show the remarkableHDN selectivity for the catalyst of this invention. The liquid hourlyspace velocity (LHSV) used in this invention was 4.

EXAMPLE 4

In this experiment, the LCCO feed was hydrotreated at LHSV ranging from1 to 6 with a catalyst prepared by impregnating a chromia on aluminasupport material with a Ni(en)₃ MoO₄ salt.

The Ni(en)₃ MoO₄ salt was prepared by dissolving 40.6 g of ammoniumparamolybdate in a mixture of 900 ml ethylenediamine (en) and 100 mlwater in a 2 liter round bottom, three-neck flask. Next, 56 g of nickelchloride was dissolved in 100 ml H₂ O and transferred to a droppingfunnel. While vigorously stirring the molybdate solution with an airdriver stirrer, the nickel chloride solution was added to the flask viathe dropping funnel. A violet powder precipitated. This precipitate wasfiltered, washed with acetone and then vacuum dried at 50° C. 94.6 gmsof product was obtained (calculated yield=94 g).

50 g of 19% Cr₂ O₃ on Al₂ O₃ in the form of 1/8" pellets (Alfa ProductsDiv. Morton Thiokol, Inc.) were calcinated at 500° C. for 3 hrs and,after cooling, crushed to a -20+40 mesh powder. This powder was thenplaced into a 500 ml ROTOVAC flask. 45.8 g of the Ni(en)₃ MoO₄ weredissolved in 120 ml of water and added to the flask. The flask wasevacuated and rotated in a 70° C. water bath until the water wascompletely removed. The final impregnated solid weighed 104.6 gms.

This impregnate was then ground, pelletized and sulfided at 360° C. forone hour following the procedure for Examples 1-3. This catalyst gave a% HDS of 70.5 and % HDN of 56.6 when tested with the LCCO feed at 325°C., 3.15 MPa and 3,000 SCF of hydrogen per bbl of oil at an LHLSV of3.0.

EXAMPLE 5

25 grams of MgO in 20-40 mesh size were impregnated with 87.2 cc ofsolution containing 30.7 grams of Ni(en)₃ MoO₄. The resulting impregnatewas vacuum dried at 50° C. overnight. The final impregnated solidsweighed 61.6 grams.

The final catalyst was sulfided at 400° C. for one hour with a 10% H₂ Sin hydrogen mixture, following the procedure for Examples 1-3.

This catalyst gave a % HDS of 58.1 and % HDN of 31.3 when tested withthe LCCO feed at 325° C., 3.15 MPa and 3,000 SCF of hydrogen per bbl ofoil at an LHSV of 3.0.

                  TABLE 1                                                         ______________________________________                                        LCCO Feed                                                                     Gravity (°API)                                                                         18.6                                                          Sulfur, wt. %    1.5                                                          Nitrogen, ppm   370                                                           ______________________________________                                        GC distillation                                                               Wt. %           Temp., °C.                                             ______________________________________                                         5              231                                                           10              251                                                           50              293                                                           70              321                                                           90              352                                                           95              364                                                           ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                                           % HDN  % HDS                                               ______________________________________                                        Catalyst                                                                      cobalt molybdate on γ-Al.sub.2 O.sub.3                                                       25.5     87.4                                            Catalyst Precursor                                                            Ni(en).sub.3 MoO.sub.4                                                                             83.0     86.8                                            Co(en).sub.3 MoO.sub.4 supported on γ-Al.sub.2 O.sub.3                                       40.3     90.9                                            ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                                           % HDN  % HDS                                               ______________________________________                                        Catalyst                                                                      cobalt molybdate on γ-Al.sub.2 O.sub.3                                                       19.0     83.6                                            Catalyst Precursor                                                            Ni(en).sub.3 MoO.sub.4                                                                             69.6     80.2                                            Co(en).sub.3 MoO.sub.4 supported on γ-Al.sub.2 O.sub.3                                       25.5     85.1                                            ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                                          % HDN  % HDS                                                ______________________________________                                        Catalyst                                                                      cobalt molybdate on γ-Al.sub.2 O.sub.3                                                      12.8     81                                               Catalyst Precursor                                                            Co(en).sub.3 MoO.sub.4                                                                            82.4     87.6                                             ______________________________________                                    

What is claimed is:
 1. A process for preparing a supported,self-promoted catalyst, said process comprising:(i) compositing aporous, inorganic refractory oxide support with a water soluble catalystprecursor salt characterized by (ML) (Mo_(y) W_(1-y) O₄) wherein Mcomprises one or more divalent promoter metals selected from the groupconsisting of Mn, Fe, Co, Ni, Cu, Zn and mixtures thereof, wherein y isany value ranging from 0 to 1, and wherein L is one or more neutral,nitrogen-containing ligands at least one of which is a chelatingpolydentate ligand; and (ii) heating said composite formed in (i) in anon-oxidizing atmosphere in the presence of excess sulfur in the form ofone or more sulfur bearing compounds and at a temperature of at leastabout 200° C. to form said self-promoted catalyst.
 2. The process ofclaim 1 wherein said promoter metal M comprises at least one metalselected from the group consisting of (a) Fe, Co, Ni and mixturesthereof and (b) mixtures of (a) with Zn, Cu, Mn and mixtures thereof. 3.The process of claim 2 wherein L has a total denticity of six and is oneor more chelating, polydentate alkyl amines.
 4. The process of claim 3wherein said sulfur bearing compound comprises H₂ S.
 5. The process ofeither of claims 3 or 4 wherein said support comprises alumina.
 6. Theprocess of either of claims 1 or 2 wherein said support compriseschromium oxide.
 7. The process of claim 6 wherein said chromium oxidesupport is supported on a refractory, inorganic oxide support material.